Telephone-exchange system



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L. POLINKOWSKY TELEPHONE EXCHANGE SYSTEM Filed June 57 1919 .1%. .Nxl n @um s MUTI# June 30, 1925.

June 30, 1925. y 1,543,869

L. POLINKOWSKY TELEPHONE EXCHANGE SYSTEM Filed June 5, 1919 5 Sheets-Sheet 2 @I f l N m N N m f w m \m y MM Affy.

Jun@ so, w25.. 1,543,869

L. POLINKOWSKY TELEPHONE EXCHANGE SYS TEM Filed June 5, 1919 5 Sheets-Sheet 3 IN2. H1415.

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Patented June 30, 1925. UNITED ySTATES PATENT OFFICE.

I IPA POLINKOWSKY, OF NEW YORK, N. Y, ASSIGNOR TO WESTERN ELECTRIC COM- v PANY, INCORPORATED, OF NEW YORK, N. Y., A. CORPORATION OF NEX/V YORK.

TELEPHONE-EICHANGE SYSTEM.

Application filed .Tune 5, 1919. Serial N'o. 301,933.

To all wao-m` t may concern.' t

`Be it known that l, Lira PoLINKowsxY,

a citizen of Russia, residing at New York,

in the county of New York, State of New 5 York, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems employing automatic switching apparatus for establishing talking connections between subscribers lines. More particularly it has to do with a telephone system vinvolving a plurality of exchanges, and in which facilities are provided for the establishment of talking connections between subscribers lines belonging to an exchange equipped with switches of one character and subscribers line belonging to exchanges equipped with switches of a different character. y f

An object of the invention is the provision, in a system of the foregoing character, of means whereby a subscribers line at an exchange utilizing step-by-step operated switches may be extended directively over such switches to a distant exchange provided with power driven switches, together with means for cont-rolling the select-ive operation of such power driven switches for further extending said line into connection with a called line at the second exchange.

A feature of the invention relates to an arrangementin which a calling subscriber is enabled to directively operate step-by-step switches 'to extend his line, and thereafter to cause the setting of a controlling mechanism, which in turn becomes effective to control the selective operation of other switches to further extend said line.

A further feature consists in the provision of means for operating selective switches in accordance with certain digits of a desired number and for setting a switch controlling mechanism in accordance with the complements of otherdigits of said number for the purpose of extending a telephone connection to the called line.

A still further feature consists in providing means, in a system where a controlling mechanism for controlling selective switches is normally selectable when said switches are in their restored position, for rendering such controlling mechanism selectable prior to the 'l restoration of said switches.

- Such other and further features as are contemplated by the present invention will become apparent from the following description and the appended claims.

In the drawings Fig. l shows a calling subscribers line terminating in a non-numerical switch at the exchange, a selector switch of the step-by-step type and the circuits of an impulse repeater.

Fig.A 2 shows in detail, the circuitsyof a first group selector of the power driven type, located at a distant exchange and associated with the incoming end of a trunk line from the exchange illustrated in Fig. l, together with the diagrammatic showing of succeeding power-driven selector switches.

Fig. 8 shows in detail, a register controlling equipment and its associated circuits for controllingthe selective operation of the power-driven switches, and also means for positioning said registers in accordance "ith a desired designation.

Fig. et showsga port-ion of the equipment at an operators posit-ion in the step-by-ste omce including the calling end of one of the cord circuits'. An illustration is also given of the manner in which the trunk circuits at the operators position are connected to the conductors leading to a first selector switch, such as shown in Fig. l.

In accordance with the general principles ofv this invention, there is provided a telephone system in which it is possible to accomplish joint working between exchanges equipped with switching mechanism of the step-by-step character, and exchanges equipped with switching mechanism of the power-driven type. Vhen a subscriber to an exchange of the step-by-step character desires to hold conversation with a subscriber'whose line belongs to an exchange provided with power driven switches, he manipulates his calling transmitter in the usual manner to send series of impulses corresponding to the digits of the desired number. Depending upon the relative capacities of the two exchanges involved, a part of these impulse series are effective to set up the step-by-step switches in the exchange to which the calling line belongs to extend the connection over an interconnecting trunk line to the desired distant exchange. Thereafter the remaining impulse series Yof the called number operate to position the registers of an idle controlling mechanism.

These registers, when thus positioned, become eii'ective to control the selective movements of vswitches in the called exchange which are operated by power in aV continuous movement to complete the establishment t the connection to the called line.

In systems where step-by-step 'switches are used, it is the general practice to arrange the selective switches for operation in accordancewith the digits of the called number.

hat is to say, the first selector, for example, is directively operative through a number of steps corresponding to the first digit of a desired number as listed in the telephone directory. Consequently, the calling dials at the substation are ydesngned to transmit impulses inA correspondence with the digits of the line designations listed in the directory, However, in power-drive exchanges of the character disclosed inthe present system, the switchA controlling registers are arranged tocontrol the selective switches in accordance with the complemerts of the digits ktransmitted Jfrom the substations. The use of such a register controlling equipment makes it necessary for the calling transmitters at the substations of lines belonging to the exchange to be designed to transmit to the exchange series of impulses which correspond to theV complements of the digits of called line numbers.

It becomes obviousthatsince the calling transmitters of lines belonging to the stepby-step exchange are arranged to send impulses in the regular way, each series containing a number of impulses corresponding to the desired digits, whereas the controlling registers in the power drive-exchange are designed to receive impulses according to the complements of the desired digits, means must be provided where a'call is extended Jfrom a stepi-by-step exchange to a power-drive exchange, to make correction for such of the impulse series of the called number as are to be eitective in controlling the power driven switches. To this end therefis provided at the power drive exchange means for receiving the series of impulses incbming `from the distant-eXtchange of the step-by-step type, and which is operative to control the positioning of the successive switch controlling registers in accordance with the complements of the number of impulses in each series. By such an expedient, the registers are set up to positions where they are effective to subsequently control theV selective switches according to the digits of a. called number, the same as it' they had been positioned under the control of a transmitter at the substation of a line belonging to the power-drive exchange. Y

' Referring to Fig. `1, wherein a calling subscribers line to an exchange is extended over line or finder switches and selector switches to the desired called line, there is also shown a modification providing for the use of Operators in the establishment of connections. Considering the system as one of the full automatic type, the operators cord circuit shown in F ig. 4, may be disregarded, whereas in considering it as a semi-automatic system, it will be understood that connections with calling lines are made in the well known manner by the insertion of the answering end of the operators cord circuits, not shown in the disclosure. In this case, the necessary alterations in the circuits shown in Fig. 1 are illustrated by the dotted line.

The switches in the second oirice may be of the construction shown and described in the patent to McBerty, No. 1,097,868, granted May 26, 1914. The general manner in which switches of this type are controlled is described inthe patent to Polinkowsky, No. 1,365,269, granted January 11, 1921.

It will lirst be assumed that the subscriber to a line, such as line 111, ot the step-bystepl exchange, wishes to converse with the subscriber Vot line 211 belonging to an exchange equipped with power-driven switches. On removing his receiver to 1nitiate the call, the brushes 131,132, 133 oit the line switch are automatically connected to the terminals of a trunk leading to an idle first selector switch. A circuit is then conipleted from battery through the lett hand winding oi line relay 100 o' the selector switch, side switch arm 102 (position V1), brush 132, overthe loop of the calling line, brush 131, sidefswitch arm 1.01 (position 1), right hand winding of relay 100 to ground. Relay 100 attracts its armature and closes a circuit from battery, through the winding or slow-to-release relay 103, to ground at the front contact and armature of relay 100. Relay 103 completes a circuit from ground, battery 119, side switch arm 106 (position 1), Contact and outer armature of relay 103, test brush 133, through the winding ot magnet 13-1 to ground. The magnet 1311 serves to maintain the connection of the line switchin any well known manner. The

Vcalling subscriber operating his dial for the first digit causes the line relay 100 to intermittently release and attract its armature. On the first release oi the armature of said relay, a circuit is closed from ground, armature and back Contact of relay 100, innerY lil() i armatures attracted during the short interruptions oie their energizing circuits. When the last impulse has been sent and the line relay maintains its armature attracted for a suiiicient period, the slow`to-release relay 104i reti-acts its arma-ture and the escape magnet deenergizes to advance the side switch into position 2.

In position 2 or" the side'switch, a circuit is established from battery, side switch arm (position 2)', through the winding ot the secondary stepping magnet SM, theV armature and contact ot said ina-gilet to ground.` The stepping' magnet SM interrupts its own circuit and operates to advance the brushes121, 123 and 125 over the successive terminals in the selected group. When the side switch nieves into position 2, the escape magnet ESC is cnergized in circuit including side switch arm 12'? (position 2) and the secondary oit-normal contact SUN. As the selector switch is moved through its lirst step, contact SGN is opened and the esca-pe magnetV depends thereafter for its energization upon a circuit including side switch arm 107, and the testbrush 125. lf the trunk individual to the iirst set ot terminals in the selected group is busy, relay 109 of the repeater will be energized and the escape magnet ESC remains energized in a circuit to ground over the left-hand armature and contact of relay 109 and resistance 118. The secondary magnet SM therefore continues to operate until test brush reaches a non-grounded terminal, where upon the escape magnet deenergizes and moves the side switch into position 3.

In this position a circuit is completed from battery through the lett hand winding of relay 108 of the repeater, brush 121, side switch arm 101 (position 3), brush 131, over the loop of the calling substation, brush 132, side switch arm 102 (position 3), brush 1.23, right hand winding ot relay 103 to ground. Relay 108, energizing, closes a circuit ,for slow-to-release relay 109which by attracting its armature places a ground on the multiple test terminals to ender the selected trunk busy. ln passing out ot' position 2, the side switch arms 101 and 102 open the circuit or relay L100, which in turn, opens the original energizing circuit oit' the slowto-release relay 103. Before relay V103 can deenergize, however, a new circuit is com pleted therefor from battery. throughthe winding ot relay 103,A side-switch arm 107 (position `3), brush 125, lett hand armature and Contact of relay`109 to ground through the resistance 113. ln position 3 of the side switch, magnet 13% of the line switchis maintained energized in a circuit troni battery through the winding ot relay 103, sideswitch arm 1.06 (position 3), contact and outer armature of relay 103, brush 133 through the winding et magnet 131i to ground. The resista-nce of magnet and relay 103 are so adjusted with respect to resistance 118 that magnet 13d will remain energized in the circuit. justtraced, but relay 103 will rnot receive suilicient current to remain energized in series with magnet 13% `While in the disclosure only one step-bystep selector switch is shown, it is to be understood that any number of such switches might be included between the primary switch and the repeater at the outgoing end of the trunk 200.

1When the line relay 108 of the repeater energizes, it closes at its outer armature a bridge across the outgoing end of the trunk line 200. Line relay 201 at the distant ei;- change is thereby energized in a circuit 'from battery'through the left hand winding thereof, back contact and inner armature of relay 202, over the lower conductor of trunk 200 through the windings of relay 117 and impedance 128, contact and outer armature oi' relay 108 upper conductor ot trunk 200, back contact and outer armature of relay 202, right hand winding of relay 201, contact 223 (1) of sequence switch 220 to ground. Relay 201 closes a. circuit from ground, normal contact ot relay 213, ar1nature and front contact of relay 201, left hand armature and back contact of relay 204i, lett hand armature and back contact ot relay 207, contact 224iv (1) winding et relay 203 to battery and ground. Relay 203 prepares circuits for relays 205 and 208. These rclays are each individual to two register' controlling mechanisms, the relay 205 serving to associate the register to which it is individual with the cord circuit when such register is idle, and the relay 208 serving to associate the register to which it belongs when the iirst register is busy. Assuming the register mechanism shown in detail in Fig. 3 which is the one controlled by relay 205, is idle at this time, a circuit is closed trom ground, inner armature and contact of relay 203, through the left hand winding of relay 205, conductor 217, contact 322 (1) of sequence switch 320, back contact and left hand armature of relay 339, contact 358 of sequence switch 350 to battery. Relay 205 energizing closes a locking circuit for itself in series with relay 339 independent ot the armature and contact of relay 203. rThis circuit may be traced from battery, contact 358 (1) armature and front contact of relay 339, through the winding of said relay, in parallel through the windings ot relays 204 and 206, through the right-hand winding of relay 205, front contact and armature of said ico ' relay to ground at back contact and left hand armature of relay 214. The relay 205 opens at its armature and back contact a similar locking circuit for thel lett-hand winding of the relay 203 individual to the second register controlling mechanism so that preference is given to the first controlling mechanism, shown in Fig. 3, when the same is idle. Relays 204 and 205 attract their armatures to associate the Vselected register controlling mechanism with the cord circuit of the first group selector preparatory to the receipt of impulses from the calling substation. Relay 204 by energizing also opens the above traced circuit for relay 203 which in turn releases its armatures.Y

Relay 339 by attracting its left hand armature opens thev circuit oit conductor 217 to render the controlling mechanism non-selectable to other cordV circuits. The preparation of thercircuits thus described at the second exchange has taken place in a veryV short time after the selection of the trunk 200 by the last step-by-step selector switch in the calling exchange, so that the calling subscriber may continue to proceed uninterrupted with the operation of his dial to send the second, third, fourth and iifth digits of the called number. Since the last four series of impulses are-operative to control the power-driven switches in the called exchange, and since as already explained the registers must be set up to a position complementary to the number of impulses contained in each of these successive series, there is provided a sequence switch 150 for this purpose, responsive to the impulses incoming from the calling exchange, and automatically associable in succession with the controlling registers 110, 120, 130 and 140.

The calling subscriber operating his dial to send the second ldigit causes the intermittent operation of line relay 103 at the repeater. On the irst retraction of the armatures of relay 108, the slowto-release relay 116 is energized in a circuit over the Contact and right-hand armature or" relay 109 to ground at the baclr contact and inner armature of the relay 103. rEhe relay 11G closes a shunt around the windings of relay 117 and impedance 123 to removel said impedance from the impulse circuit during the time the calling subscriber is operating his dial. lWhen relay 204 is energized, it closes a circuit from ground, normal contact of relay 213, armature-and front contact of relay 201, left-hand armature and front contact of relay 204, conductor 21.9-, through the winding oit relay 334 to battery and ground. The relayw334 is constructed to attract its armature slowly. Relay 201, being energized long enough 'for this purpose, relay 334 energizes and closes a circuit from ground, over its armature and front contact, sequence switch contact333 through the winding of sequence switch 320 to battery, to drive sequence switch 320 out oit position 1 into position 2. At the lirst deenergization of relay 103, relay 201 releases its armature andrcloses a circuit from ground, normal contact of re-layp213, armature and back contact of relay 201, right-hand armature and contact of relay 204, conductor 218, right hand winding, armature and contact of relay 329, contact 323 (1 to 3) of sequenceV switch 320 through the winding of sequence switch 150 to battery. In parallelto this circuit, a circuit is also closed for the left-hand winding of relay 329 to ground at the normal' contact of relay 213. `Relay 329 being differential does not attract its armature when both windings are energized.

lVhen. relay 201 retracts its armature `on the first impulse, relay 334 deenergizes and closes a circuit from ground over its armature andv back contact, and contact 333 (2) to drive sequence switch 320 out of position 2 and into position 3. The movement of sequence switch 320 from` position 2 to 3, does not disturb the circuit above traced for sequence switch 150, since contact 323 is closed in position 1 to 3. Sequence switch 150 energizes and moving out of position 0 closes at its local contact 151, a short circuit around the right-hand winding ofV differential relay 329. This relay attracts its armatureY and sequence switch 150 continues to move under thecontrol of its local contact into position 1. Relay 329 deenergizes and at the second retraction of the armature of relay 201 yin response to the second impulse of the series, the above traced circuit is again closed to drive sequence switch 150 out of position 1, where it causes the energization of relay 329 as described. Under the control of local contact 151,7sequence switch 150 advances into position 2. This operation proceeds, the sequence switch 150 moving through one position for each impulse sent out from the calling subscribers station, and finally comes to rest in a positionV corresponding to the digit transmitted. The relay 334 being slow to attract its armature, does not again energize dueto the brief closures of its circuit by relay 201 during theimpulse series. At the end of the series, however, when relay 201 attracts its armature for a relatively long period, relay 334.*again has time to energize, and in so doing closes a circuit over its armature and front contact, and contact 333 (3) to drive sequence switch 320 outof position 3 and into position 4. The sequence switch 150 which'. like the registers 110, 120, 130 and 140, is provided with 1 0 circuit-controlling positions, now runs Vthrough the remaining switch 150, from the position to which it has been set, hack to its normal position, may be traced from battery, through the winding of said sequence switch, contact 152, contact 336 (4) to ground. In passing through its successive half positions on its way baci; to normal, sequence switch 150 intermittently closes a circuit for register 110 traceable from battery, through the winding of said register, contact 323 (4) and contact 153 of sequence switch 150 to ground. Upon reaching its zero position, sequence switch 150 closes a circuit from battery, through the winding of sequence switch 320, contact 337 (4) and contact 154 (0) to ground, to drive sequence 320 into position 5. The positioning of the first register 110 under the control of the sequence switch 150 has taken place during the time the calling subscriber is adjusting his dial after the transmission of the second series of impulses so that the apparatus at the called exchange is now in readiness to receive the third series of impulses.

When the first interruption Vof the trunk circuit 200 occurs during the sending of the third series of impulses, relay 201 retracts its armature and completes a circuit from ground, normal contact of relay 213, armature and hack contact of relay 201, righthand armature and contact of relay 204, through the right-hand winding, armature and contact of relay 329, contact (5) to the sequence switch 150. Art the same time, the energizing` circuit of the relay 334 is opened, and by retractingits armature this relay closes a circuit over sequence switch Contact 333 (5) to drive sequence switch 320 out of position 5 into position 6. The sequence-switch 150 energizes, and again moves from position 0 into position 1. In

the manner described with respect to the preceding series of impulses, the sequence switch 150 advances one step for each impulse, coming to rest in the position depending upon the third digit of the called number. At the end of the third series when relay 201 attracts its armature for a comparatively long period, the relay 334 again energizes and closes a circuit over its armature and front contact and sequence switch contact 333 (6) to drive sequence switch 320 out of position 6 into position 7. In position 7 of sequence switch 320 a circuit including contact 336 (7) and contact 152 is completed to drive sequence switch 150 back to its normal position 0. lWhen passing through each of its successive half positions sequence switch'150 closes a circuit from ground, contact 153, contact 323 (7), throughthe winding of the second register 120`to battery and ground. The register 120 isthereby set up to a position corresponding to the complement of the third digit. On reaching' position 0, sequence switch 150 closes a' circuit including contact 154 and Contact 337 (7) to drive switch 320 into position 3.

)When the fourth series of impulses is sent, the relay 201 retracting its armature for the first interruption opens the circuit of relay 334 which by deenergizing closes a circuit including its armature and back contact and contact (3) to drive sequence switch 320 out of position 8 and into position 9. Relay 201 also closes a circuit over its armature and back contact including the right hand winding, armature and contact of relay 329, and sequence switch contact 323 (9) for energizing the sequence switch 150. Under the control of stepping relay 201, sequence switch 150 is advanced to the proper position. At the end of the fourth series of impulses, relay 201 attracts its armature for a time sumcient for the energization of relay 334. Relay 334 closes a circuit from ground over its armature and front contact, contact 333 (9) to the winding of sequence switch 320 to drive said sequence switch out of position 9 and into position 10. In position 10 of sequence switch 320, a circuit is closed at contact 336 to again drive the sequence switch 150 back to its normal position to control the setting of the tens register 130. In passing through its half positions, while returning to position 0, sequence switch 150 intermittently opens and closes the circuit from ground, contact 153, contact 328 (10) through -the winding of register 130 to battery and ground. Register 130 is driven to a position corresponding to the fourth digit of the called number. When sequence switch 150 reaches position 0, a circuit is completed from ground, Contact 154 (0), contact 337 (10) through the winding of sequence switch 330 to battery and ground. Sequence switch 320 moves into position 11.

The final series o'f impulses are now transmitted froml the calling suhscribers station. At the first retraction of the armature of relay 201 in response to the first interruption of such impulse series the relay 334 is deenergized and closes a circuit including Contact 333 (11) to drive sequence switch 320 out of position 11 and into position 12. The first retraction of the armature of relay 201 also closes a circuit including the right-hand winding, armature and contact of differential relay 329 and sequence-switch contact 323 (12) for energizing the winding of sequence switch 150. In the manner now well understood, sequence switch 150 is advanced to its proper position under the con- 'trol of the stepping relay 201. When the last impulse of the final series has been sent, and relay 201 retains its armature attracted, the slow to energize relay 334 energizes to close a circuit including contact 333 (12) for driving sequence switch 3,20 into position 13. In position 13, sequence switch 150 is energized in a circuit including its con-l tact 152 and contact 336 and runs through the remainder of itscycle to its O position to control the setting of theunits register 140. The circuit for advancing the register 140 under the control of the sequence switch 150, may be traced :tromV ground, contact 153, Contact 323V (13), through the winding of the register 140 to battery and ground; On reaching its 0 position, sequence switch 150 closes a circuit including its contact 154 (O) and contact 337 (13) /or driving thesequence switch 320 into position 14. I

When the sequence switch 320 reached position 2, a circuit` was closed from ground, contact 347 (2) of sequence switch 320, con tact 352 (l) ot sequence switch 350, through the winding of sequence switch 350 to battery and ground. Sequence'switch 350 advances into position 2 by means of this circuit. In this position of sequence switch 350 relay 222, Fig. 2, is energized in a circuit from battery, through the winding of said relay, contact 225 (1) of sequence switch y 220, lett-hand armature and back contact of relay 215, lett hand armature and contact of relay 206 through the winding` of relay 355, armature and contact of relayV 362, contact 357 to ground. Relay 222 closes a circuit from ground,iover its armature and front contact, armature and back contact of vrelay 232, contact 226 through the winding of sequence Yswitch 220 toV battery, whereby sequence switch 220 is driven out ot position l and into position 2. In posi-V tion 2 of sequence switch 220, the above trace-d circuit for relay 222 is opened at contact 225 permitting relay 222 to deenergize. circuit is thereupon closed from ground, armature andback Contact of relay 222, contact 227 (2), through the winding of sequence switch 220 tobattery to drive said sequence switch into position 3. )Vhen relay 355 energizes in position 2 oit sequence switch 350, a circuit is closed from battery, through the winding of sequence switch 350, contact 354 (2), left-hand winding of relay 362, front contact and armature of relay 355 to ground, therebyV `energizing sequence switch 350 to drive it out ot' positionw2 and into position 3. In parallel to this circuit, a circuit is also closed from. battery through the riOht-lnind windinOa of rela Y 362 ContactV C3 b E 7 354 (2), through the left-hand winding of relay 362 to ground at the armature of relay 355. The relay 362 is made differential, and will not attract its armatureV when both windings are energized to open the above traced circuit for relay 222 which resulted in the driving of sequence switch 220 out of position 1 and into position 2. This expedient provides that sequence switch 220 is driven as described'into position 2 before sequence switch 350 leaves positionV 2. The

sequence switch 350 remains `in position 3 until sequence switch 320 Varrives in position 5, at which time a circuit is closed from ground, contact 347 of sequence switch 320, contact 352 of sequence switch 350 through the winding of sequence switch 350 i winding of relay 355, arn'iature and contactV ot relay 362 to ground at contact 357 Relay 222 by energizing closes a circuit from ground over its armature and front contact, armature and back contact of relay 232, contact 225 through the winding of sequence switch 220 to battery to drive Y sequence switch 220 into position 4.

In position 4 of sequence switch 220, the trip spindle power magnet 248 of the rst Vgroup selector is energized in a circuit from battery, through the winding of said magnet, contact 247 (4), front contact and armature of relay 222 to ground. The trip spindle rotates in a continuous movement to select'the proper set of brushes, and for each brush tripping position passed over, the interrupter contact 255 provides a circuit to ground including Contact 249 for relay 222, in shunt ot the stepping vrelay 355 at the register' set. Relay 222, however, remains energized while at the first closure of the contact 255, relay 355 releases its armature. The retraction of the armature of relay 355 completes a circuit from battery through the winding of the register 110, contact 112, contact 361 (4), Contact and armature and lethand winding of relay 359bacl contact and armature oiY relay 355 to ground. In parallel to this circuit a circuit is also closed from battery, contact 363 (4) through the right hand winding of relay 359 to ground at the armature of relay 355. The relay 359 being differential does notA operate when both of its Vwindings are energized. The register 110, however, energizes inthe circuit traced and moves out o't the position to which it 'was adjusted under the control ofsequence switch 150. Then the local contact 136 of register 110 is closed, the left-hand winding of Vrelay 359 is short-circuited permitting said relay to attract its armature. Under the control of its local contact. the register 110 advances to its next position. )Wien the shunt in the fundamental circuit is removed by the opening of the contact 255 of the interrupter, the stepping relay 355 energizes and causes the deenergizat-ion of rc-V lay 359. At the next short circuiting of relay 355, register 110 is again energized and advances in the manner described through another position. This procedure continues until register 110 has reached its 0 position.

`ing group of selector switches.

VThe sequence ytion 6.

Upon the next retraction ot' the armature of relay 355, after register 110 has reached its 0 position, a circuit is closed from battery, through the Winding of vsequence switch 350, contact 354 (t), Contact 114i (0), contact 361 (4t), contact and armature and left-hand winding of relay 359, back contact and armature of relay 355 to ground. In parallel thereto a circuit is closed from battery, through the right-hand winding of relay 362 to ground at the armature of relay 355. rlhe relay 362 operates to open the fundamental circuit, while sequence switch 350energizing in the circuit traced moves out ot position e and into position Then the interrupter contact 255 opens after relay 362 has been energized to interrupt the tundamental circuit, relay 222 deenergizes and closes a circuit from ground over its armature and back contact, contact 22'7 (4) through the winding of sequence switch 220 to battery to drive said sequence switch into position 5.

in position 5 of sequence switch 220, the brush carriage power magnet 261 is energized by means of a circuit from battery, through the winding ot said magnet, contact 226 (5), back contact and armature of relay 232 to ground at the front-contact and armature of relay 222. It will be noticed that relay 222 immediately energized as sequence switch 228 moved into position 5 over a circuit including contact 225 (5) and the back Contact and armature of relay 216. The brush carriage of the group selector rotates to advance the selected set of brushes over the terminals of trunks to the succeed- When an idle trunk is found, which idle condition is identified by means of a selectable potential on the test terminal, the test relay 234 is energized in a circuit over the test terminal 280, test brush 281, through the lett-hand high resistance winding of relay 234 to ground at sequence switch contact 238 (5). Test relay 2341- attracting its armature closes a low resistance path to ground through its right-hand winding armature and contact, winding of relay 232, and sequence switch contact 238, in shunt of the circuit traced through the high resistance winding of the relay 23%. This low resistance path serves in the well known manner to reduce the potential of the multiples ot the seized trunk to render the same non-selectable toother switches. Relay 232 by attracting its armature, opens the circuit of the power magnet 261 to bring the brush carriage to rest and at its front contact closes a circuit from batt-ery, through the winding of sequence Yswitch 220, contact 228 (5), front contact and armature of relay 232, to ground at the front contact and armature of relay 222.

switch 220 moves into posi- The fundamental circuit is now extended over contacts 279 and 278 to the second group selector 282, in the well known manner. rllhis fundamental circuit leads from the second group selector 282 over the brush 283, contact 278 (6) left-hand armature and back contact of relay 215, letthand armature and contact ot relay 206, through the winding` of stepping relay 355, armature and contact ot' relay 362, contact 357 (7), contact and right-hand armature ot relay 206, back contact and right-hand armature or" relay 215, contact 270 (6), brush 284-, and thence to the selector 282. It is to be noted that the sequence switch 350 was driven into position 7 as soon as sequence switch 320 reached position 8, by means of a circuit from ground, contact 3410, contact 356 (5), through the winding of sequence switch 350 to battery. Brush selection takes place at the second group selector 282 in the well known manner, the stepping relay 355 in the fundamental circuit being deenergized for each brush tripping position passed over by the tripping spindle. At each retraction of the relay 355, a circuit is closed from ground, armature and back contact of said relay, lett-hand winding and armature and contact ort dil'lerential -relay 359, contact 361 (7), contact 122, through the winding of register 120-to battery and ground. Then the register 120 reaches position 0, the next retraction ot the armature of relay 355 thereafter closes a circuit from battery, through the winding ci sequence switch 350, contact 351i (7), contact 114- (0), contact 124 (0), contact 361 (7), armature and Contact and left-hand winding ot relay 359 to ground over the bach contact and armature of relay The sequence switch 350 energizes and moves out ot position 7 and into position 8. In parallel to the circuit just traced, the Aiight-hand winding ot' relay 362 is also energized in a circuit including contact 3511 (7). Upon the sequence switch 320. reaching position 1.1, the sequence switch 350 energized in a circuit over contact 341 (11) and contact 351.2 (8) and moves into position 9. At the termination of trunk selection at the second group selector 282, the fundamental circuit is extended to the final selector 285, and the stepping relay again energizes.

rlfhe brush tripping spindle ot the final selector is rotated in the well known inanner, 'and the stepping relay 355 in the fun damental circuit is intermittently deenergized and energized. At each deenergization of relay 355, the circuilJ is closed from ground, armature and back contact et relay 355, lefthand winding and armature and contact ot relay 359, contact 360 (9), contact 137, through the winding of the tens register 130 to battery and ground. The register 130 upon reaching its 0 position closes a circuit from battery, through the Winding ot se- Yswitch contacts 279 and 27S.

quence switch 350, contact 364 (9), contact 133 0), contact 360 (9) to ground at the back contact and armature ot relay 355. Sequence switch 350 energizes in this circuit and moves into position 10. Relay 362 is energized to open the fundamental circuit by means of a circuit through the righthand winding of said relay, contact 364 (9) andV thence to ground atV the arma-ture and contact ot relay 355 as above traced.

rllhe sequence switch V350 remains in position 10 until sequence switch 320 has reached Vposition 14, at which time a circuit is closed 'from ground over contact 343 (14) and contact 350 (10) to drive sequence switch 350 into position 11. In position 11 ot sequence switch 350, the fundamental circuit is again closed at Contact 357'. The brush carriage of the final selector 285 rotates in the usual manner and for each retraction ot the armature of the relay 355, caused by the shortcircuiting interrupter contact, a circuit is completed from ground, armature and back contact of relay 355, lett-hand winding and armature and contact of dill'erential relay 359, cont-act 360 (11), contact 143 of the units register 140, through the winding of said register to battery and ground. The register 140 is restored to its 0 position, and Vupon reaching such position a circuit Vis closed from battery, through the winding of sequence switch 350, contact 364 (11), back contact and righthand armature of relay 374, contact 144 (0), Contact 360 (11) and thence to ground at the back contact and armature of relay 355. Relay 302 is energized in parallel to the circuit traced to open the fundamental circuit, whereas the sequence switch350 moves from position 11 into position 1. A circuit is now closed from battery through the winding ot sequence switch 320, contact 337 (14-15) to ground at contact 369 The sequence switch 320 moves over position 15 and comes to rest in its normal position 1.

On leaving position 11, sequence switch 350 opens at its contact 358, the energizing circuit of relays 339, 204, 206 and 205. The relay 339, deenergizing, renders the register controlling mechanism which is now restored to its normal position selectable by other cord circuit-s. The relay 205 retracting its armature closes a circuit from ground, lefthand armature and back contactY of relay 214, armature and back contact of relay 205, armature and back contact of relay 203, contact 235 (G), through the winding ot sequence switch 220 to battery. Sequence switch 220 is driven from position into position 7, where the right-hand winnings of the repeating coil 229 are connected through to the inal selector over sequence- When the brushes ot the final selector 285 are set upon the terminals or" vthe called line, the connecting circuit is closed momentarily in any Vdesirable manner to cause the energization battery, through the winding of sequence' switch 220 contact 235 (7), V'liront contact and armature of supervisory relay 242,`

front contact and armature ot relay 222 to ground, whereby sequence switch 220 advances into position 3. When supervisory relay 242 again deenergizes, sequence switch 220 is moved Ainto position 10 by means of a circuit including contact 223 (8), back contact and armature of relay 242, front contact and armature of relay 222 to ground. On leaving position 9, the sequence switch 220 opens at contact 223 the circuit in series with the right-hand winding of the line relay 201 which, up to this time, has been maintained in shunt ot the highresistance winding of the relay 213. The high resist ance relay 213 is now introduced in series with the trunk circuit 200, but is without effect at this time.

It the called subscriber responds, the removal of his receiver from` the switchhook closes a circuit tor the supervisory relay 242. A circuit is thereupon completed from battery through the winding of sequence switch 220, contact h,35 (10), front contact and armature ot relay 242, front contact and armature of relay 222 to ground. VSequence switch 220 moves into position 13 where the shunt around the high resistance 213 is again completed over contact 223 (13), front contact and armature of relay 242 and front Contact and armature of relay 222 to ground. In position 13, a circuit is completed Jfrom battery through the winding of relay 202, contact 249 (13), contact 225 (13), back contact and armature of relay 216 to ground. Relay 202 attracts its armatures and reverses the direction of current over the trunk line 200 from the windings of line relay 201. This current reversal may be made use of for message registration or for any other purpose desiredf At the termination of the conversation, the release of the established connection takes placeV due to the calling subscriber replacing his receiver on the switchhool. The relay 10S is deenergized as soon as the calling subscriber hangs up his receiver and causes in turn the deenergization of slowto-release relay 109. Relay 109 opens the holding circuit of relay 103 at its left-hand armature. The relay, 103 being unable to retain its armatures attracted when in series with magnet 134 deenergizes and closes a circuit for the release magnet REL. This circuit may be traced from battery through said release magnet, primary ott-normal contact PON back contact .and inner Varmature of relay 103, to ground and back contact and malaises.

armature,` of relay 10,0. Magnet REL rearmature and Contact ofrelay, 103, the line switch is alsorestored to its normal position.`

As the linerelay 108aty the repeater retracts its armature andrelay 201 deenergizes` permanently, a circuit is closedv from battery through, the winding, of slow-to-operate( relay 210,"sequence switch contact 221, back 'contact and armature of relay 201, to ground at the normal contact of relay- 213. Relay.

210 closes a circuit at itsarmature and contact for the right-hand winding of slow op-f erating'relay 214.` Relay 214, energizing,

closes a locking circuit for itselfover itsy left-hand armature and front contact and left-hand winding, through the windings of relays 216 and 215 to battery and ground. Relay 216 energizes and*` opens theiherei-nforetraced'y circuits of relays 222 and 202. Relay 222 closes ay circuitfrom ground over its armature and back Contact, contact 227 (.13),k through thev winding of. sequence switch 220 to t battery to c drive such sequence switchinto position16. In position16,.the

brush carriage of theV group selector'isre-l turned to its normal Vposition by means of a circuit established from battery, through the winding of the brush carriage power magnet 261, Contact 226 (1 6), back contact and armature of,` relay 232150(y ground over the front contact and armature of relay 222. It will be observed that therelay 222- energized inV a circuit including contact 238 1as sequence switch 220 passed into positionV 16. In the normal position of the brush carriage al circuit isk completed from battery,

tactyof relay 238 (16). Relay232 attractf Y ing its armature, opens the circuit of power magnet 261 and also closes a circuit todrive sequence switch 320 out of position 16 and into position 1. -This latter kcircuit may be traced from battery,` through the winding of said sequence switchcontact 228 (16), front contact and armature/of relay 232 to ground overy the front contact and armature of. relay 222. The release of the second group selector-282 andthe final selector '285 may take place in any suitable manner.

Translation from the decimalV systemV to the order of grouping made use of in selector switches of the character used in this system, is accomplished by meansof relays 376 and 374 at the register controlling 'mechanism.V If, for eXample,the thousandsdigit is odd, thel contact 135 of the register 110 will` be closed,r `A s sequence switch 3 50 passes through position 31/2 in this case, relay is energized in 'circuit over Conf tact-378 and. Contact 13.5, and locks up over its right-hand armature to groundy at sequenceswitch contact'36'8. lVitlrthe relay 37 Genergized, sequence switch 350 is drivenl out of position 4 andinto position 5 Vas soon as the register 110 reaches position 9, rather than position 0, asin the caseot an even digit.v Hence the tripping spindle of the first group selector is `stopped in the samebrush tripping position as though the vlower even digithad'been sentfrom the calling substation. Later, afterv register`120 hasbeen restored to'0`, the register 110 is driven from positionv 9' to` position 0 by means of a circuit including the back contactand armature of relay 376, which deenergize'dl when sequence switch contact 368 left vposition 45` contact 113, (9), contact 124 (0),l contact 361 (7) to ground at the armature of relay 355. Therefore the tripping spindle` of thesecond group selector is advanced through an, additional position.

YIf the'hundreds digit of the called number is odd, contact 126 ot the register 120 will"V be closed, and relay 374 is energized in a` circuitincluding contact 353 asV sequence switch 350 passes through position 6.A Relay 374 locksv up in a circuit over its leftliand armature" and contact to ground `at contact 146. In `passing throughposition 61/2 sequence switch 350 momentarily closes its contact 381, and register 120 is driven through, an, additional position by means of a circuit including. contact122, contact 381 left-hand armature andcontact of relay 37 4 to, ground at contact 146. This causes. the register 12,0 to advance `to the next even position, which. causes the brush tripping spindle. of the second group selector to be moved under the control of the register 120 to the same brush tripping position as. it' the number dialled had. been the lower even figure. Laten during unitselection when the register 14,0"1'eaches position 0, it continues to rotate through a complete additional cycle by means of a circuit including the front contact and right-hand armature of relayl 374and contact 144- (0). By this meansthe brush carriage of the final selector is driven to carry the selected set of brushes to the proper "set of terminals in the odd hundredssection of the terminal bank. As theregister 140 passes from position 0,' to position 1, contact 146 is opened to open the circuit of` relay 174 which consequently deenergizes.k

It will be recalled that whena calling subscribersY line is extended over the step-by- Vstep switches to a trunk line suoli as 200, leading to a distance exchange equipped with switches of* the power-driven type, the resulting energization ofthe line relay 201 associated withV the trunk` 200,'` causesy the energization of relay 203. The operation of' relay 203 causes the energizationfofV two relays 205 and 2,08 for selectingl one or the ian other of two register controlling "mechaf nisms which serve thev cord circuit of .the4

firstgroup selector shown in Fig. 2. It will tion. Y In other words, one of the two registerV controlling mechanisms allotted to .a Acord circuit is normally selectable by said cord circuit when the rst group selector is in its` restored position and its controlling sequence switch is in position 1. In a systemof-this character where an established connection may comprise, in part, a series of step-by-step switches and, in part, a series of power driven switches, it is apparent that upon release, the step-by-step switches are restored to normal in a very -brief space of time, whereas a longer intervalcis required or they brush carriages of the powerdriven'switches to rotate back to their restored positions. It may occur that after the stepfby-step' switches have released,` a second call is extended to the cord circuit of the first group selector. employed inthe previous call before such groupselector has had sufficient time to restore.` In accordance with the present invention provision is made whereby the cordv circuitV ofv a y.first group selector may be seized, and anidle register controlling mechanism associated therewith, during Vthe interval that the group selector is restoring to its normal position. Assume that the release of lan established connection has just. been ini-i tiated, in which case, as above described,re`

lays 214, 216 and l215 are energized in series with each other. Relay 216 opens theA circuit of relay 222 which by releasing closes a circuit to start sequence switch 220 out of position 13. positions 9 to 14, the high resistance relay 213 is short-circuited by a path to ground over theright-hand armature and front contact of relay 215 and sequence switch contact 238. If a call is eX- tended to trunk 200 whilesequence switch 220 is in position 13, relay 213 does not energize in series with relay 201 and a circuit for relay 203 is completed from ground, normal Contact of -relay 213, armature and front contact of relay 201, left-hand armature and back contact of relay 204, left-hand armature and back contact of relayv 207, contact and right-hand armature of relay 214,

through the winding of relay 203 to battery and ground. Relay 203 operates as already explained to select a linecontrolling mecha` nism. The relay 213 does not energize in series `with relay 201 in positions 14 to 18 of sequence switch 220 ,since it is short-circuited to ground at sequence switch contact 223. Should fa call be extended over the trunk 200 while sequence switch 220 is' in either position 14, 15 or r16, relay 2034 is energized in the circuit above tracedV 'over russes' the contact and right-handk armature of re-V lay 214. When se uence switch220 reaches position 17, the le t-hand winding of relay 214 is shunted out byl a rdirect path to ground over contact 231 which results in relay 214 releasing its armatures. `If now,f'a i call comes in while sequence switch 220` is in position 17 or position 1 8, the enervization of relay 201 closes `a circuit rom ground, normal Contact of relay 213, front contact of relay 201, left-hand armature and b aclr contact of relay 204, left-hand armature and back contact of relay 207, contact 224 (17-18), through the winding of relay It will now belassumed that the step-by` step `exchange shown in Fig. 1 is of the semi-automatic type where. calls on subscribers. lines appearbefore and are handled by operators in the'usual manner; for this purpose there isshown diagrammatically, the calling end `of an operators `cord circuit 141, including the calling plug 142, adapted nto be inserted in jacks such `as 143 which'ylead to the first selector switches as shown by the dotted lines 147, 148 andv 149. In. this embodiment of the system a conductor Y145 such as shown by the dotted line leads from theV back contact of relay 117 to the non-grounded side of resistance 118.

l When a call appears before the operator, she answers it in thel well-known manner by inserting the answering plug,` (not shown), in the jack `of the calling line. Upon learning the number of the desired line,she inserts the calling plug 142 in the jack 143 and operates her impulse sender 155 to transmitthe required digits. The operators sender 155 serves exactly the same as a calling subscribers transmitter to set the step-by-step switches in the first ex change, and `to control the positioning of a register set in the distantexchange.,` After the operator has completed the sending of impulses she closes key 156, which includes relay 157 in series with theV windings of relay 108 at the repeater.` If the called line is -found to be idle, sequence switch 220 of the group selector goes into position 10, as explained, where kthe high resistance relayr 213 is included in series with relay 201 and relay 117 at the repeater. Relay `117 being marginal releases its armature and closes a circuit from battery through the winding of yrelay 103, side switch arm107 (position 3), lbrush 125, left-handarmature and contact of relay 109, conductor 145 to ground l UU Les-435869 at the armaturevoit` relay 117. This path to ground short-circuits the supervisory relay 158 which would otherwisev beenergi'zedi in series with relay 103' over a circuit from battery through the winding ofrelay 103, side-switch armv 106 (position 3), contact andjouter armature'of relay. 103, conductor 149, sleeve ot jack` 143 and plug 142, through the winding of relay 158 to ground. Relay 158 by beingdeenergized'closes a circuit for the lamp'V 159 which indicates to the operatorthat ringing current is being placed Iupon the called line. Then the called subscriber answers and sequence switch 220 moves into position 13, the highresistance relay 213 is short-circuid over contact 223 (13) front contactand armature, of' relay242`, front contact and armature otrelay 222 to ground. The removal of the resistance otrelay 213, permits relay 117 at the repeater to energize and open the conductor 145. This includes theresistance Y118 ina circuit. parallel to the circuit traced for the` supervisory.v relay 15S'. The

, resistance 118 being sufficiently high,` relayv 158110w receives enough current Vto energize andex-tinguish lamp 159; TheV effacement of lamp 159 indicatesto theoperator `that the called party yhas responded. At'

the terminationy of conversation, the connection is releasedby the removal ofplug 14:2A

from the jack 14 V VVhatisclaimed is: Y y

1. In` av telephone exchange system,{a calling line, a plurality ofstep-by-step switches, means for directively operating said switches to extend the calling line, a plurality'ofjV switches eacharrangedfito .b e driven in a con.

tinuousV `movement, a switch-controlling mechanism, means for variably, setting said" mechanism, and means controlled by said mechanism for selectively controlling the operation of'said last .namedswitches to furthen extend the calling line.

2. In a' telephoneexchange systeima calling line, a plurality of'step-by-step switches, means under the control of' the calling line for directively operating said switches to .ex-

tend; the calling line, a plurality of. switches,

eacharrangedto bev driven in a continuous movement, a switch controlling` mechanism.means;under the control ofthe rcalling line tor variably setting said mechanism, and means controlled` by said mechanism. for.vr selectively controlling the operation of said last, named switches to. further extend. the calling line.

3. In a telephone exchange system, a calli ing line a plurality ofv step-loy-step switches, meansftcr directively operating said switches to extend the calling line, a plurality, of switches each arranged to be driven in 'a continua-insA movement', a set o f registers, means. for variably. positioning said 'registers, and means under the control' of said for diiectively operating said" switches to extend the calling line,I a plurality of switches each arranged" tvo be driven in a continuous movement, a set 'of' registers', means under the control of the calling line for variably positioning-,said registers, and means, under the control of said registers for selectively cent-rollingthe operation ofi' saidlast named switches to further extend the` calling line.

5. Ina telephone exchange system, an exchange having step-by-stepswitchesthe-rein,y a subscribersfline terminatingrin the exchangea distant exchange having'switches therein each arranged't'o be driven in a Vcontinuous movement, a switch-controlling` mechanism, 4a trunk interconnecting said exchanges, means for operating saidstep-b'ystep switches to connect the calling line over said'trunlr* to said distant exchange, means for variably setting said controlling mechanism, and meansunder the control of saidv mechanism for selectively controllingk the operation of' said last named switches to further extend the calling line.

6. In a telephone exchange system, anexchange havingA step-by-step switches therein, a subscribers line terminating in the exchange, a distant exchange having switches Sdi therein each arranged to be driven in a continuous movement, a switch-controlling mechanism, a trunk,interconnecting said exchanges, means undery the control oisaid linel for operating said step-by-step switches to connect the Vcalling line over saidl trunk to said distant*l exchange, means under the control off said line for variably setting saidi controlling mechanism and meansunder the control of: said mechanism for` selectively controlling the operation off said4 last namedV switches to further extend the calling line.

7.' In a telephone exchange system,a plurality otstep-by-step switches for-extending subscribers lines, a plurality of switches each arranged to be driven ina continuous movement :tor extendingv subscribers7 lines, a sender arranged to send impulse series in accordance with the designations of" called lines, means responsive to certain impulse series sent by said sende-rfor operating said step-by-step switches, and means responsivel to other impulse series sent by thesender for contro'llingfthed operation off said continuously driven switches. Y

8. vIn a telephone exchange system, a plu'- rality of step-by-step switches for extending subscribers" lines, a plurality-of` switches eacharranged" to be driven in a continuous movement forextendingsubscribersj lines, a

switch-controllingmechanism, a sender arranged to send impulse series in accordance with the designations ofcalled lines, means responsive to certain impulse series sent by said sender for operating said step-by-step switches, means responsive to other impulse series sentby said sender for setting said y controlling `mechanism, and means responsive to said controlling'mechanism Jfor controlling `the operation of said vcontinuously driven switches.

9. VIn a telephone-exchange system, a subscribers line,ia sender associated with saidKVV line arranged to transmit impulse series in accordance with the designations of called lines, step-by-step switches orextending said line, switches each varranged to be driven in a continuous movement for further extending saidv line, means responsive to cercontrolling the operation of said continu-g ously driven switches.

10. In a telephone exchange system,1a subscribers line, a sender associatedtherewith arranged to be Avariably operated toA send a group otimpulse series corresponding to the digits of'a called number, step-by-,step

switches, switches each arranged to be driv-` en in a continuous movement, means responsive to a definite number of the irstseriesoic said group for operating said step-by-step switches to Aextend said line, and means responsiveto the remainingimpulse series ot said groupV fory controlling the-.operation of said continuously driven switches to further extend said subscribers line.

f 11. Ina telephone exchange system, a sub# scribers line, switches lfor Lextending said line, acontrolling mechanism comprising' a plurality of registers eachv having aseries of controlling positions, vmeans ttor sending series of impulses, means responsive to sfaid impulse series for setting said registers in positions complementary tothe number vot impulses Acontained in said impulse series, and means controlledV by .saidregisters for setting said switches.

12. In a telephone exchange system, a subscribers line, switches yfor extending said line, a controlling"mechanism comprising a plurality of registers each having a series of controlling positions, a sender associated with each line for sending series of impulses, means responsive to said impulse seriesfor setting saidregisters in positions complementary to the number vof impulses contained in said impulse series, and4 means controlled by saidregistersctor setting the said switches.

13.-' In a telephone'exchangesystem, a subscribers line, switches for extending said linea controllingmechanism comprising a LIS-ass@ plurality of registers each having a series of cont-rolling positions, means for sending` series of impulses, means assooiable successively with the registersv of said, set and responsive to said impulse series for setting said registers in positions complementary to the number of impulsescontained in said impulse series, and means controlled bysaid registers for setting said switches.

14. In a telephone exchange system, a subscribers line, switches forextending said linea controlling mechanismcomprising a plurality off registers each having Va series of controlling positions, means .for sending j switches, a plurality of switches. each arrangedto be driven in a continuous movement, a controlling mechanism `comprising a plurality of registers each having a series of controlling positions, means Jr'or sending seriesV of impulses, means responsiveto certain of said impulse series -or setting said step-by-step switches Vto extend the subscribers line, means responsive to other of said impulse series for setting the registers of said Lset in positions complementary 'to` the, number of impulses contained in said other impulse series, and means controlledV by said registers Jfor setting saidcontinuously driven switches to further extend the subscribersline. n

`16. VIn a telephone exchange system, a subscribers line, aselective switch, .a trunk line terminating inV said switch, means for extending the subscriberls line over said trunk to said switch, a register controlling mechanism for controlling said switch, means controlled over said trunk for seizing said register controlling mechanism` when said switch is in its normal position, means for ,renderingVV said register controlling mechanism non-selectable over said trunk iis when the switch is engaged, and means for Y rendering said register controlling mechanism selectable over said trunk during the release of said switch. e

17. In a telephone system, a trunk, a selective switch in which said trunk terminates, a controlling mechanism, means'for extendinga connection over said trunk to the selective switch, means for connectingvsaid mechanism, to said trunk, means controlled by said mechanism tonoperating the selective switch, means for releasing said trunk and selective switch, means for extending another connection over the trunk while said izo voi? the selective switch.

sw-itch isr releasing, and ,means .for con-nect- Ative switch in Awhich said trunk terminates,

a ,register` controlling mechanism, ,means for extending a connection over said trunk, .means for connectmgsaid controlling mechanism to said trunk, means controlled over said Ltrunkvfor setting said mechanism,

means controlled by said mechanism for operating the selective switch, means for releasing said trunk and selective switch,

means for extending a second connection .over the trunk while said switch is releasing,

and means for connecting said register ,mechanism to said trunk during v.the release 1 9. In ,a telephone system, a trunk, a selective Vswitch in which said trunk 'terminates, `a register `controlling mechanism, means for extending a connection over said trunk tothe selective switch, means forfconnecting said mechanism tosaid trunk, means controlled over said trunk. for setting the register mechanism, means controlled .by -said mechanism for operating the selective switch, means :for releasing-said trunk and said selective switch, and means for extending another connectionover the trunk while said switch is releasing, v said controlling mechanismarranged to be connected-,to said trunk in 4response to the extension `out said second connection during the release of .theA

selective switch, said mechanism being arranged to take a setting over said trunk during the release of the selectiveswitch.

20. Ina telephone system, a trunk, a selective switch in which said trunk terminates, a register controlling mechanisnnmeans for v extending al ,connection over said ,trunk to theselective switch, means responsive to the extension of such connection for connecting said ymechanism to `the trunk, ,means for transmitting impulses over the .trunk for setting said register mechanism, means controlled by said mechanism for operating the selective switch, means for releasing said trunk and selective switch, and ,means for extending another connection over the trunk while said switch is releasing, said mechanism `being arranged to ,be connected Ato said trunk in response to rthe extension of said second connection during the release of said switch, said mechanism being arranged to take a setting in response to impulses transmitted over said trunk during the release of said selective switch.

2l. In a telephone system, a telephone line, a step-by-step switch, a second switch arranged to be driven in a continuous movement, means for directively operating said step-by-step switch to extend the telephone line to said second switch, a switch controlling mechanism, means for setting said mechanism, -,and meanscontrollcd bynsaid mechanism for selectively operating said vsecond switch to further extend the telephone line.

22. In a `telephone exchange system, a calling line, va plurality of selector switches,

v switch controlling`meohanisms` means assoswitch controlling mechanisms, each vcomprising .a plurality rof registers, a step-bystep selector switch for extending the calling Aline to said iirst-named selector switches, means associated with said ,calling line for .,drectively .operating said step-by-.step selector switch to select a controlling ,mechanism and for thereafter controlling the va-a riable setting of the Iegistersofsid -neChanisni, and means controlled by said mechanism for selectively controlling ,the operation of said first named selector switches to further extend the Acalling line.

24:. In a telephone exchange system, .a callingline, a plurality of selector switches, ,a switch controlling mechanism, means associated with said calling line `for directively operating one ofsaid switches to select said `controlling mechanism, and for thereafter controlling the variable setting of said mechanism, .and means controlled by said .mechanism for selectively controlling the operation of other of said switches to `extend a Aconnection from the kcalling line.

25. In a telephone exchange system, a calling line, a called line, a first .plurality Aof selector switches for extending said calling line toward said called line, a switch (controlling mechanism comprising a plurality l'oi registers, means associated with said calling line for directively operating Vone of said first ,plurality of switches to select said controlling mechanism and for thereafter controlling the variable setting of the registers of said mechanism, a second plurality of selector switches, and means controlled by said mechanism 'for selectively controlling the operation of said second plurality of selector switches to complete extension of said calling line to said called line.

26. In a telephone exchange system, a callingl line, a plurality of selector switches, a switch controlling mechanism, means associated with said calling line for directively operating certain of said switches to select said controlling mechanism and for thereafter controlling the variable setting of said 'iai mechanism, and', means controlledby `said Y mechanism for selectively controlling the 'operation of other of' said switchesto extend a connection .from the calling line.A

'27; In a telephone exchange system, a calling line, a called line, a first plurality of selector switches for extending said calling line toward said called line, switch coni trolling mechanisms, each comprising a plu- ,rality' of registers, means' associated with said calling line for directively operating ,certain of said iirst plurality of switches,

in accordance with the oiiice designation of said called line to select a controlling mechanism, and for Ythereafter controlling L the variable setting of the registers of sai mechanism in accordance with the numerical designation of said line, a second pluralityof selector switches and means controlled by said,` mechanism for selectively controlling the operation of certain of vsaid V"second, plurality' of selector switches to complete extension of said calling line to the "said called line.

248.51m a telephone system, a trunk, ase- `lective switchl in which said trunk terminates, `a register sender, means for extending a connection'y overv said trunk to the 'selective switch, means for connecting said sender to said trunk, means controlled over "said trunk for setting the sender, means controlled bysaid sender or'operating theV selective switch, means for releasing said trunk and selective switch, means for extending another'connection over the trunk' v while said switch is releasing, and means for connecting said sender to said trunk during the release ofthe selective switch.

I 29,1In atelephone system,"a trunk, a selective switch in Vwhich said trunk terminates, a register sender, means for extend- 4ing a connectionV over said trunk tothe selective switch, means for connecting Vsaid sender to said trunk, means controlled Vover said trunk forY setting the "sender, means controlled by said sender for'operating the selective switch, means for releasing said trunk and selective switch, and means for extending anotherconnection overl the trunk while said switch is releasing, said sender arranged. to vbe connected to said trunk in response to the extension of said second. connectioii during the release of the selective i" insitasee switch, said sender being arranged to" take a setting in response to impulses transmitted over said trunk during the release of the selective switch.

30. In a telephone system, a trunk, a selective switch in which said trunk terminates, a register sender, means for extending a connection over said trunk `to the selective switch, means responsive to the ex- Y tension of such connection for connecting said sender to the trunk, means for transmitting impulses over the trunk for set-V ting said sender, means controlled by .said sender for operating the selective switch,

means for releasing said trunk and selective l switch, and means for extending another connection over the trunk while said switch is releasing, said sender'being arranged to be connected .to said trunk in response to the extension of said second connection during the release of said switch, said sender being arranged to take a setting in response to the impulses transmitted over said trunk during the release of said selective switch.

3l. In a telephone system, anV office, a

second oiice, a two-conductor trunk interconnecting said oiiices, a selective switch in the second cnice 1nV which said trunk terminates, a register sender, means at the irst office for selecting said trunk to ex" vtend a connection thereover to the selective switch, means for connecting said register sender' to the trunk in response to the extension of such connection, means con- 4 trolled over said trunk for setting 4the sender, means controlled by said sender for operating the selective switch to further extend 'the connection, means for releasing 'said trunk at the first oiiice to cause the 

